<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Title</title>
	<style>
		.divbox {
			border: #1E9FFF 1px solid;
			box-sizing: border-box;
		}

		#yourContent {
			width: 800px;
			height: 500px;
			border: black 1px solid;
			margin: 0 auto;
		}

		html, body {
			width: 100%;
			height: 100%;
			padding: 0;
			margin: 0;
		}
	</style>
</head>
<body>
<!-- 你的容器 -->
<div id="yourContent">

	<div class="divbox" style="height: 10%;width: 100%;"></div>


	<div class="divbox" style="width: 100%;height: 80%"></div>

	<div class="divbox" style="height: 10%;width: 100%;"></div>

</div>
</body>
</html>